This is very important and is something that should have been taught prior to getting your trailer air brakes endorsement. But it might have been a while since you tested. Perhaps you work at a place where the mechanic does all the trailer air brakes testing. So here are some basic steps for testing your trailers' air brakes.
1、The first thing is your seatbelt, buckle up for safety!
2、After starting your trailer build up the pressure (90-110 lbs)
3、Check your parking brake by, applying the parking brake, shift into gear, releasing the lutch and attempting to move, it should not.
4、Charge your trailer’s air system
5、Allow the airlines to fill
6、It will take about a minute to be able to check for leaks, (no more than 2 psi)
7、Apply 90 pounds of pressure and hold for about one minute
8、3 psi should be the maximum leakage
9、Pumping the brakes, should cause the light/alarm to activate (at about 60 pounds)
10、If you keep pumping, the trailer’s protection valve should pop out (20 to 40 psi)
11、Running and in neutral check to see how long it takes for the pressure to build back up (should build to between 85 and 100 psi)
12、As the pressure builds the air governor should blow out (between 125 and 130 psi).
